Since Christmas (almost, December 23rd), USGS distributes LANDSAT 8 data corrected from atmospheric effects, as they already did for LANDSAT 5 and 7. These data have been long awaited and will be very useful.
Of course, USGS processing addresses the whole world. To access these products, you should use the earthexplorer.server. You will find the data by clicking on LANDSAT_CDR, as shown in the image on the right. You will have to order for their processing before being able to download them. Usually this processing is very quick.
We did not yet compare the USGS products developed by NASA (E.Vermote) with our Level 2A LANDAT 8 data acquired over France and produced and distributed by THEIA with CESBIO processor, but we will work into it shortly.